Merge pull request #3 from Zxc4wonder/codex/fix-line-comment-roundtrip

fix: preserve SQL semantics after line comments

Author: Zxc4wonder

core/src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java

@@ -295,6 +295,9 @@ protected final void print0(char value) {
             return;
         }
 
+        if (endLineComment && value != '\n' && value != '\r') {
+            println();
+        }
         this.appender.append(value);
     }
 
@@ -366,6 +369,10 @@ protected void print0(String text) {
             return;
         }
 
+        if (endLineComment
+                && (text == null || (!text.isEmpty() && text.charAt(0) != '\n' && text.charAt(0) != '\r'))) {
+            println();
+        }
         this.appender.append(text);
     }
 

core/src/test/java/com/alibaba/druid/bvt/sql/visitor/SQLASTOutputVisitorLineCommentTest.java

@@ -0,0 +1,134 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.sql.visitor;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
+import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;
+import com.alibaba.druid.util.Utils;
+import org.junit.Test;
+
+import java.io.InputStream;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class SQLASTOutputVisitorLineCommentTest {
+    private static final String SELECT_ITEM_LINE_COMMENT =
+            "SELECT (id - 1) -- comment\n, name FROM users;";
+
+    @Test
+    public void test_selectItemLineComment_mysql() {
+        assertSelectItemRoundTrip(SELECT_ITEM_LINE_COMMENT, DbType.mysql, 2);
+    }
+
+    @Test
+    public void test_selectItemLineComment_postgresql() {
+        assertSelectItemRoundTrip(SELECT_ITEM_LINE_COMMENT, DbType.postgresql, 2);
+    }
+
+    @Test
+    public void test_selectItemLineComment_oracle() {
+        assertSelectItemRoundTrip(SELECT_ITEM_LINE_COMMENT, DbType.oracle, 2);
+    }
+
+    @Test
+    public void test_selectItemLineComment_clickhouse() {
+        assertSelectItemRoundTrip(SELECT_ITEM_LINE_COMMENT, DbType.clickhouse, 2);
+    }
+
+    @Test
+    public void test_lineCommentBeforeFrom() {
+        assertSelectItemRoundTrip("SELECT id -- comment\nFROM users;", DbType.mysql, 1);
+    }
+
+    @Test
+    public void test_lineCommentAfterComma() {
+        String sql = "SELECT\n"
+                + "    id, -- comment\n"
+                + "    name\n"
+                + "FROM users;";
+        assertSelectItemRoundTrip(sql, DbType.mysql, 2);
+    }
+
+    @Test
+    public void test_blockCommentBeforeComma() {
+        String sql = "SELECT\n"
+                + "    id /* comment */,\n"
+                + "    name\n"
+                + "FROM users;";
+        String output = assertSelectItemRoundTrip(sql, DbType.mysql, 2);
+        assertTrue(output, output.contains("SELECT id, name"));
+    }
+
+    @Test
+    public void test_lineCommentInFunctionArguments() {
+        String sql = "SELECT\n"
+                + "    func(a -- comment\n"
+                + "    , b)\n"
+                + "FROM t;";
+        SQLSelectStatement statement = parseSelect(sql, DbType.mysql);
+        SQLSelectQueryBlock queryBlock = queryBlock(statement);
+        assertEquals(2, methodArguments(queryBlock));
+
+        String output = SQLUtils.toSQLString(statement, DbType.mysql);
+        assertTrue(output, output.contains("-- comment"));
+
+        SQLSelectQueryBlock reparsed = queryBlock(parseSelect(output, DbType.mysql));
+        assertEquals(output, 2, methodArguments(reparsed));
+    }
+
+    @Test
+    public void test_oracleNumbersResource() {
+        String resource = "bvt/parser/antlr_grammers_v4_plsql/examples/numbers01.sql";
+        InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
+        assertNotNull(resource, input);
+
+        assertSelectItemRoundTrip(Utils.read(input), DbType.oracle, 12);
+    }
+
+    private String assertSelectItemRoundTrip(String sql, DbType dbType, int expectedItemCount) {
+        SQLSelectStatement statement = parseSelect(sql, dbType);
+        SQLSelectQueryBlock queryBlock = queryBlock(statement);
+        assertEquals(expectedItemCount, queryBlock.getSelectList().size());
+
+        String output = SQLUtils.toSQLString(statement, dbType);
+        if (sql.contains("--")) {
+            assertTrue(output, output.contains("--"));
+        }
+
+        SQLSelectQueryBlock reparsed = queryBlock(parseSelect(output, dbType));
+        assertEquals(output, expectedItemCount, reparsed.getSelectList().size());
+        return output;
+    }
+
+    private SQLSelectStatement parseSelect(String sql, DbType dbType) {
+        return (SQLSelectStatement) SQLUtils.parseSingleStatement(sql, dbType);
+    }
+
+    private SQLSelectQueryBlock queryBlock(SQLSelectStatement statement) {
+        return (SQLSelectQueryBlock) statement.getSelect().getQuery();
+    }
+
+    private int methodArguments(SQLSelectQueryBlock queryBlock) {
+        SQLExpr expr = queryBlock.getSelectList().get(0).getExpr();
+        return ((SQLMethodInvokeExpr) expr).getArguments().size();
+    }
+}

core/src/test/resources/bvt/parser/clickhouse/0.txt

@@ -90,8 +90,8 @@ SELECT CASE
 		-- '${date}'
 		-- origin end
 		-- new
-		'2025-07-08' -- new end, 4
-		), '1231'))
+		'2025-07-08' -- new end
+		, 4), '1231'))
 	END AS date_e
 ------------------------------------------------------------------------------------------------------------------------
 select physical_wh--,wh_type